U.S. high school students engage in very high rates of AIDS risk behavior and HIV has been found in this population. Despite this, there have been exceedingly few interventions in high school settings that have actually demonstrated, in methodologically, vigorous research, significant effects on students' AIDS risk behavior. This proposal applies the Information-- Motivation--Behavioral Skills (IMB) model and the Natural Opinion Leader (NOL) model of AIDS risk behavior change to design, implement, and rigorously evaluate promising new interventions to reduce AIDS risk behavior in high school students. The IMB model assumes that AIDS preventive behavior is a function of students' levels of AIDS risk reduction information, motivation, and behavioral skills. An IMB model- based intervention delivered in high school health classes will attempt to remediate empirically identified deficits in these elements in students to increase their AIDS preventive behavior. The NOL model assumes that if popular attractive, natural opinion leaders (NOLs) in a high school population take a proprevention stance, social norms-with respect to AIDS preventive behavior will change, and AIDS prevention will increase. In the NOL approach, in addition to engaging in proprevention interactions with friends and acquaintances at school, high school NOLs will also communicate key AIDS prevention information to friends and acquaintances and teach them key behavioral skills. Complementing the IMB- and the NOL-model-based interventions, a combined IMB/NOL model- based intervention, integrating the elements of both models, will be delivered to determine if the combined strengths of these two approaches result in the greatest AIDS risk behavior change. Both the IMB and NOL models have been successfully used to change AIDS risk behavior in other populations, both seem easy to modify for use with a high school population and there are compelling reasons to believe that the application of these two models (and their integration) in this population may produce effective, easily implemented, and easily disseminated interventions to change AIDS risk behavior in high school settings. Specific Aim 1 of the proposed research involves conducting elicitation research with students in multiracial high schools to identify deficits in AIDS risk reduction information, motivation, and behavioral skills that are associated with AIDS risk behavior in this population. These findings will be used in part to determine the content of the IMB, NOL, and combined IMB/NOL model-based interventions. To provide further guidance for the design of the NOL and combined IMB/NOL model-based interventions, elicitation research will focus on identifying ecologically valid strategies for NOLs to employ to change AIDS prevention social norms and to impart key information and behavioral skills in informal interactions with peers. Specific Aim 2 involves designing, piloting and implementing the IMB, NOL, and combined IMB/NOL model-based interventions on a wide scale in multiracial high school settings. Specific Aim 3 involves conducting intervention outcome research to assess the efficacy of the three interventions, when compared with no treatment controls, across multiple direct and indirect indicants of AIDS preventive behavior.